You may not realize it, but Facebook knows exactly what you look like and can pick you out of any picture posted online.

That includes photos you upload and even photos taken by people you don't know. But, how does it work and is there anything you can do about it? 

So someone takes your picture. No wait, you're out somewhere and someone takes a picture of someone else but you're in the background. Then they post it to Facebook.

Did you know it's entirely possible that Facebook will tag you in the photo? Does that sound a little creepy? You may not realize it, but that feature is turned on for your account.

Facebook quietly rolled out the technology to some users last year.

Imagine this: you're in a crowd and someone does a Facebook Live. If you're in the background, Facebook can spot you and put your name and profile with your picture.

But Facebook says it won't give that information to anyone else in the photo or anyone taking the photo without your permission.

Here's how to turn it off: Go to settings and you'll see "Face recognition" in the column on the left. You can turn it on or off. For everyone up until now, it's been turned on by default. Facebook says "off" is the default setting now, but only for new Facebook users.

Face recognition replaces "Tag suggestions". Like when a friend posts a group photo, Facebook will examine the faces in it and give suggestions as to who's in it. Of course, Facebook may have hundreds of photos of you, so picking you out in a crowd is easy. If you are identified in someone's photo or video, you'll be notified.

Facebook promises to protect your privacy. If that's not good enough for you, or if you worry that someone else can get the information, you can turn it off with a few clicks. Smile: Facebook is always looking for you.